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PubMed2001

The applications of capture-recapture models to epidemiological data.

Capture-recapture methodology, originally developed for estimating demographic parameters of animal populations, has been applied to human populations. This tutorial reviews various closed capture-recapture models which are applicable to ascertainment data for estimating the size of a target population based on several incomplete lists of individuals. Most epidemiological approaches merging different lists and eliminating duplicate cases are likely to be biased downwards. That is, the final merged list misses those who are in the population but were not ascertained in any of the lists. If there are no matching errors, then the duplicate information collected from a capture-recapture experiment can be used to estimate the number of missed under proper assumptions. Three approaches and their associated estimation procedures are introduced: ecological models; log-linear models, and the sample coverage approach. Each approach has its unique way of incorporating two types of source dependencies: local (list) dependence and dependence due to heterogeneity. An interactive program, CARE (for capture-recapture) developed by the authors is demonstrated using four real data sets. One set of data deals with infection by the acute hepatitis A virus in an outbreak in Taiwan; the other three sets are ascertainment data on diabetes, spina bifida and infants' congenital anomaly discussed in the literature. These data sets provide examples to show the usefulness of the capture-recapture method in correcting for under-ascertainment. The limitations of the methodology and some cautionary remarks are also discussed.

Adult↗

PubMed1995

Solid-phase hybridization capture of low-abundance target DNA sequences: application to the polymerase chain reaction detection of Mycobacterium paratuberculosis and Mycobacterium avium subsp. silvaticum.

Polymerase chain reaction (PCR) has been widely applied to the detection of microorganisms. Overall sensitivity of PCR tests may be substantially reduced due to a large excess of nontarget DNA and inhibitory substances in the sample. We used a 5'-biotinylated 513-bp probe from the 3' region of the IS 900 element specific for Mycobacterium paratuberculosis (Mptb) to capture target Mptb DNA from crude sample DNA extracts. Captured target DNA was separated using streptavidin-coated magnetic particles (Dynal). Since the IS 900 element shares homology over this region with IS 902 in Mycobacterium avium subsp. silvaticum (Mavs), target DNA from this other pathogen was also retained. Highly specific PCR for the detection of either organism directed to the 5' regions of IS 900 or IS 902 was then performed directly on the solid phase. Hybridization capture of target DNA using sequence adjacent to the desired specific PCR site applied to Mptb increased overall sensitivity of detection in tissue and fecal extracts 10- to 100-fold. False positives due to contamination artifact were substantially excluded since the capture probe did not retain amplicons from the detection PCR. Development of the method to involve covalent 5' immobilization of capture probes on heat-resistant polymers should, in the future, provide a simple system with broad potential applications.

Animals↗

PubMed2000

A vesicle capture sensor chip for kinetic analysis of interactions with membrane-bound receptors.

A novel sensor chip for use in surface plasmon resonance (SPR) biosensors has been developed to capture vesicles which may contain membrane-bound receptors. Sulforhodamine-containing vesicles were shown by fluorescence microscopy to be immobilized intact on the sensor chip. Binding of cholera toxin to captured vesicles containing ganglioside GM(1) was demonstrated using SPR, and the derived kinetic and affinity constants were similar to literature values. Biotinylated vesicles captured on the sensor chip were used to bind streptavidin and then biotinylated ss-DNA. The hybridization of complementary ss-DNA to the immobilized ss-DNA was then analyzed using SPR. The values obtained were similar to those obtained for an identical interaction analyzed using a commercially available streptavidin-containing sensor chip. Binding of vancomycin-group antibiotics to captured vesicles containing a bacterial cell wall mucopeptide analogue was demonstrated. No binding of the bacterial endotoxin Cry1A(c) to captured vesicles containing its cell surface receptor could be demonstrated.

Animals↗

PubMed1999

A preliminary description of responses of free-ranging rhesus monkeys to brief capture experiences: behavior, endocrine, immune, and health relationships.

A cohort of free-ranging rhesus monkeys has been followed since birth in 1994 on the island of Cayo Santiago, Puerto Rico. At 3 years of age, subjects were trapped and blood samples were collected after capture and prior to release the following day. Blood samples were processed for natural cytotoxicity toward xenogeneic tumors, phenotyping, and plasma hormones. Intestinal parasites were determined from fresh stool samples collected during trapping. Data were also available from the previous year for antibody titers to latent viruses prevalent in this population. Behavioral traits of each monkey were characterized using a previously developed trait scale for rhesus monkeys. Natural cytotoxicity toward both K562 and Raji targets declined from capture until release the following day. Plasma cortisol rose and plasma prolactin and growth hormone fell during the period of captivity; a rise in insulin was significant. It was expected that individual differences in behavioral traits might predict immune and hormone levels at the time of capture or changes in these parameters during the capture period. Although behavioral adjectives tended to cluster along three orthogonal dimensions (Insecurity, Irritability, and Sociability), they bore no relationship to the physiological parameters collected acutely (in vitro immune and endocrine parameters). The individual difference markers of gender and maternal rank were not related to the magnitude of the observed changes in these in vitro parameters, either. However, an in vivo measure (CMV titer) was related to individual differences in Irritability. It was concluded that the magnitude of the stress associated with capture overwhelmed the individual difference effects.

Animals↗

PubMed1993

Microplate capture hybridization of amplified parvovirus B19 DNA fragment labelled with digoxigenin.

A capture hybridization technique in microplate has been developed for the identification of polymerase chain reaction (PCR) amplified B19 DNA fragment in clinical specimens. The amplified 104 bp B19 DNA fragment, located in the gene coding for structural proteins, was directly labelled during the amplification reaction by incorporation of digoxigenin-labelled dUTP. The amplified product was then captured by a probe immobilized on microplate wells. The capture hybridization reaction was visualized as an enzyme-linked immunosorbent assay using anti-digoxigenin Fab fragment labelled with peroxidase. Thirty-five serum samples were tested by our capture hybridization assay and the results were in accordance with the results obtained by Southern blot analysis of PCR amplified product. Our microplate capture hybridization assay showed a high sensitivity and reproducibility and appears to be a practical and reliable test for routine screening of B19 parvovirus DNA in clinical specimens.

Base Sequence↗

PubMed2004

A functional analysis of the crown architecture of tropical forest Psychotria species: do species vary in light capture efficiency and consequently in carbon gain and growth?

The crown architectures of 11 Psychotria species native to Barro Colorado Island, Panama were reconstructed from field measurements of leaf and branch geometry with the three-dimensional simulation model Y-plant. The objective was to assess the role of species differences in architecture in light capture and carbon gain in their natural understory environment. When species were grouped according to their putative light environment preference, the shade tolerant species were found to have a small but significantly higher efficiency of light capture for both diffuse and direct light as compared to the light demanding species. Within each grouping, however, there were few significant differences in light capture efficiency among species. The lower efficiencies of light demanding species was due to slightly higher self-shading and slightly lower angular efficiencies. Simulations of whole plant assimilation showed that light demanding species had greater daily assimilation in both direct and diffuse light due to the significantly greater light availability in the sites where light demanding species were found, as compared to those where shade tolerant species occurred. Among light demanding species, the above ground relative growth rate measured over a 1-year period by applying allometric equations for mass versus linear dimensions, was positively correlated with diffuse PFD and with mean daily assimilation estimated from Y-plant. For the shade tolerant plants, there was no significant correlation between RGR and mean daily assimilation or with any measure of light availability, probably because they occurred over a much narrower range of light environments. Overall, the results reveal a strong convergence in light capture efficiencies among the Psychotria species at lower values than previously observed in understory plants using similar approaches. Constraints imposed by other crown functions such as hydraulics and biomechanical support may place upper limits on light capture efficiency.

Biometry↗

PubMed2007

Recognition and capture of breast cancer cells using an antibody-based platform in a microelectromechanical systems device.

Cancer is one of the most common diseases afflicting humans. The use of biomarkers specific for tumor cells has facilitated their identification. However, technology has not kept pace with the field of molecular biomarkers, leaving their potential unrealized. Here, we demonstrate the efficacy of recognizing and capturing cancer cells using an antibody-based, on-chip, microfluidic device. A cancer cell capture biochip consisting of microchannels of size 2.0 cm long and 500 microm wide and deep, was etched onto Polydimethylsiloxane. Epithelial membrane antigen (EMA) and Epithelial growth factor receptor (EGFR) were coated on the inner surface of the microchannels. The overall chip measured 2.0 cm x 1.5 cm x 0.5 cm. Normal and tumor breast cells in a phosphate buffered saline (PBS) suspension were flowed through the biochip channels at a rate of 15 microL/min. Breast cancer cells were preferentially captured and identified while most of normal cells passed through. The capture rates for tumor and normal cells were found to be >30% and <5%, respectively. This preliminary cancer cell capture biochip design supports our initial effort of moving a BioMEMS device, from the bench top to the clinic.

Animals↗

PubMed1994

Occlusion, transparency, and stereopsis: a new explanation for stereo capture.

Stereo capture occurs when a regular pattern of repeating elements with zero disparity is superimposed on a disparate subjective figure. The elements enclosed within the subjective contours, but not those outside them, are perceptually captured and pulled on the same depth plane of the disparate figure. The phenomenon has been interpreted as the result either of a spreading of disparity signals from the subjective figure or of the attribution of the depth of certain salient image features to the finer texture elements enclosed in them. We suggest here that, instead, the fact that stereo capture is limited to the texture elements lying within the boundaries of the subjective figure is simply due to ambiguous occlusion information at the monocular level. When the texture elements occlude the inducers of the subjective figure as well, the elements lying outside the boundaries of the subjective figure are also captured. We propose that stereo capture arises as the solution to a conflict between information provided by retinal disparity and occlusion, and show how this effect is related to other previously observed phenomena of conflicting cues to depth.

Cues↗

PubMed1994

Motion capture of luminance stimuli by equiluminous color gratings and by attentive tracking.

Two experiments demonstrated motion capture of luminance-defined dots by gratings with no net luminance-based motion. In a series of two-frame experimental trials, we superimposed bright dots and a color grating rotating in opposite directions. Capture was observed at equiluminance and was facilitated by the presence of color in gratings over a range of luminance contrasts. In a second experiment, observers noted that when a counterphase grating was tracked in either direction with attention, the superimposed dots were captured in that direction. These results suggest motion capture is supported not only by luminance-based motion, but also by color- and attention-based motion. Indeed, we suggest that the most parsimonious explanation is that all capture is mediated by attention.

Attention↗

PubMedDate not supplied

The immunochemistry of sandwich ELISAs--V. The capture antibody performance of polyclonal antibody-enriched fractions prepared by various methods.

Studies compare the performance of antibody-enriched serum fractions prepared by various methods, when adsorbed on polystyrene microtiter wells as capture antibodies (CAbs) and tested against multivalent antigens. The criteria of performance in the RIA used included antigen capture capacity (AgCC) and the nmol of functional capture sites per microtiter well (CAbt). Affinity purified polyclonal (pAb) and monoclonal antibodies (mAb) were employed as reference CAbs. AgCC was highest for enriched fractions prepared using caprylic acid and a high-pressure SpG affinity column. The performance of capture antibodies is expressed by an equation which was empirically derived and experimentally tested; CAbt x AgCC/ng adsorbed IgG. In terms of this parameter, CAb-enriched fractions prepared with caprylic acid performed best. The data reported also provide insight into solid-phase ligand immunochemistry. Adsorbed polyclonal CAb performed with remarkable homogeneity in percent bound and in Scatchard plots. Values obtained for CAbt from Steward-Petty plots were directly correlated with the length of the LBR of log-log percent bound plots but indicated that less than 10% of the potential capture sites of polyclonal CAbs remained functional after adsorption; mAb showed a more serious loss of activity. The loss of CAbt was a general phenomenon for all preparations tested although relative to their antibody content, certain antibody-enriched fractions retained a higher proportion of CAbt than their affinity-purified counterparts. Comparative studies in which the activity of adsorbed mAb and pAb was compared to the same antibodies immobilized by a non-adsorptive procedure, indicated that adsorbed CAbs also express lower affinity. The studies we report offer a single parameter criterium for comparatively evaluating CAb performance while simultaneously revealing the need to develop immobilization procedures that can preserve CAbt and antibody affinity so that immunoassays with wide dynamic ranges and high AgCC can be developed without waste of antibody.

Adsorption↗

PubMed1986

Physiological stress responses in big gamefish after capture: observations on plasma chemistry and blood factors.

The plasma electrolytes, Na+, K+, Ca2+, Cl- and osmolarities had high values in capture-stressed big gamefish. Blood metabolites measured after stress showed glucose and lactate elevations. The activity of the plasma enzymes alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase and lactate dehydrogenase suggested tissue disruptions following severe capture stress. Haematocrit values and methaemoglobin were high in capture-stressed gamefish. The plasma chemistry of resting and capture-stressed snapper (Chrysophrys auratus) was studied for comparison. Specific differences in plasma biochemistry appeared to be the result of different strategies of fish behaviour during capture.

Animals↗

PubMed1996

Effects of misdiagnoses on disease monitoring with capture--recapture methods.

Capture--recapture methods are increasingly employed to correct for underascertainment of prevalent or incident cases in epidemiological surveillance. Routine systems of disease surveillance, such as morbidity registries or mortality statistics, are, however, often prone to errors in disease diagnosis. This article provides a quantitative assessment of the performance of the two-source capture--recapture method for disease monitoring in the presence of false-positive and false-negative diagnoses in one of the two sources. Expected capture--recapture case counts and traditional case counts are algebraically derived as functions of the individual case ascertainment probabilities of both sources and of the probabilities of diagnostic misclassification. It is shown that misdiagnoses can lead to underestimation or overestimation of case numbers by the capture--recapture approach, depending on the specific circumstances of disease monitoring. Nevertheless, the net bias is typically less severe than with traditional case counts. The findings are illustrated with examples from the field of cancer registration. Strategies are discussed that might minimize the problem of misdiagnoses in the design of capture--recapture studies or that might be used to correct for it in the analysis.

Death Certificates↗

PubMed2005

Mass spectrometric analysis of affinity-captured proteins on a dendrimer-based immunosensing surface: investigation of on-chip proteolytic digestion.

The monolayer of fourth-generation poly(amidoamine) dendrimers was adopted to construct the immunoaffinity surface of an antibody layer. The antibody layer as a bait on the dendrimer monolayer was found to result in high binding capacity of antigenic proteins and a reliable detection. The affinity-captured protein at the immunosensing surface was subjected to direct on-chip tryptic digestion, and the resulting proteolytic peptides were analyzed by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The performance of the on-chip digestion procedure was investigated with respect to the ratio of trypsin to protein, digestion time, composition of a reaction buffer, and the amount of affinity-captured protein on a surface. Addition of a water-miscible organic solvent to a reaction buffer had no significant effect on the digestion efficiency under the optimized digestion conditions. The on-chip digestion method identified the affinity-captured bovine serum albumin (BSA), lysozyme, and ferritin at the level of around 100 fmol. Interestingly, the detected number of peptide hits through the on-chip digestion was almost similar regardless of the amount of captured protein ranging from low- to high-femtomole levels, whereas the efficiency of in-solution digestion decreased significantly as the amount of protein decreased to low-femtomole levels. The structural alignment of the peptide fragments from on-chip-digested BSA revealed that the limited exterior of the captured protein is subjected to attack by trypsin. The established detection procedures enabled the identification of BSA in the biological mixtures at the level of 0.1 ng/mL. The use of antibodies against the proteins involved in the metabolic pathway of L-threonine in Escherichia coli also led to discrimination of the respective target proteins from cell lysates.

Amino Acid Sequence↗

PubMed2005

Top-down contingent capture by color: evidence from RT distribution analyses in a manual choice reaction task.

According to the contingent capture hypothesis, observers can specify their control settings in advance of the target's presentation to quickly attend to relevant target colors. Two predictions were derived from this hypothesis and tested in a manual choice response task. First, contingent capture by color was expected: capture of spatial attention by a better-matching color stimulus should be stronger than capture by a less-matching color stimulus. Second, with the control settings specified in advance, the contingent capture by color should commence early after the stimulus onset and should be evident among fast correct responses in an RT distribution. Both predictions are shown to hold true in two experiments. Results are discussed in light of contrasting evidence for saccadic instead of manual responses.

Adult↗

PubMed2004

Hybrid capture 2 viral load and the 2-year cumulative risk of cervical intraepithelial neoplasia grade 3 or cancer.

OBJECTIVE: The purpose of this study was to determine the clinical value of a semiquantitative measure of human papillomavirus viral load by the hybrid capture 2 assay for stratification of the risk of histologic cervical intraepithelial neoplasia grade 3 or carcinoma. STUDY DESIGN: The Atypical Cells of Unknown Significance and Low-Grade Squamous Intraepithelial Lesions Triage Study was a randomized clinical trial of 5060 women with 2 years of follow-up to evaluate treatment strategies for women with equivocal or mildly abnormal cervical cytologic condition. The usefulness of the continuous hybrid capture 2 output relative light units/positive controls that were above the positive threshold (1.0 relative light units/positive controls), which was a surrogate for human papillomavirus viral load, for distinguishing between hybrid capture 2 positive women who were diagnosed with cervical intraepithelial neoplasia grade 3 or carcinoma during the study from those who were not diagnosed with cervical intraepithelial neoplasia grade 3 or carcinoma was examined with the use of receiver-operator characteristic analyses. RESULTS: Relative light units/positive controls values did not further discriminate between hybrid capture 2 positive women with cervical intraepithelial neoplasia grade 3 or carcinoma from those with less than cervical intraepithelial neoplasia grade 3 or carcinoma. The use of a cervical intraepithelial neoplasia grade 2 or more severe or carcinoma case definition did not alter our findings. CONCLUSION: Among women with atypical cells of unknown significance or low-grade squamous intraepithelial lesion cervical cytologic findings, the hybrid capture 2 viral load measurement did not improve the detection of 2-year cumulative cases of cervical intraepithelial neoplasia grade 3 or carcinoma significantly.

DNA, Viral↗

PubMed2006

Error-processing of oculomotor capture.

Previous research has shown that salient events have a powerful effect on our covert (attentional capture) and overt (oculomotor capture) behavior. The goal of the present study was to examine whether oculomotor capture errors, which are purely stimulus-driven, meaning that they are not in any way defined by the task-set, elicit the error-related negativity (ERN). Using a hybrid of antisaccade and oculomotor capture tasks, we showed that erroneous prosaccades and irrelevant onset capture errors elicited the ERN of similar amplitude. The results suggest that participants adopted an internal standard for a direct eye movement to the target (optimal performance) and any eye movement that deviated from this path was detected by a performance-monitoring system and indexed by the error-related negativity.

Adult↗

PubMed2004

Interplay between plasma hormone profiles, sex and body condition in immature hawksbill turtles (Eretmochelys imbricata) subjected to a capture stress protocol.

We investigated plasma hormone profiles of corticosterone and testosterone in immature hawksbill turtles (Eretmochelys imbricata) in response to a capture stress protocol. Further, we examined whether sex and body condition were covariates associated with variation in the adrenocortical response of immature turtles. Hawksbill turtles responded to the capture stress protocol by significantly increasing plasma levels of corticosterone over a 5 h period. There was no significant sex difference in the corticosterone stress response of immature turtles. Plasma testosterone profiles, while significantly different between the sexes, did not exhibit a significant change during the 5 h capture stress protocol. An index of body condition was not significantly associated with a turtle's capacity to produce plasma corticosterone both prior to and during exposure to the capture stress protocol. In summary, while immature hawksbill turtles exhibited an adrenocortical response to a capture stress protocol, neither their sex nor body condition was responsible for variation in endocrine responses. This lack of interaction between the adrenocortical response and these internal factors suggests that the inactive reproductive- and the current energetic- status of these immature turtles are important factors that could influence plasma hormone profiles during stress.

Age Factors↗

PubMed2006

On the survival of peptide cations after electron capture: role of internal hydrogen bonding and microsolvation.

Electron capture by both bare and microsolvated small peptide dications was investigated by colliding these ions with sodium vapor in an accelerator mass spectrometer to provide insight into processes that occur on the microsecond time frame. Survival of the intact peptide monocation after electron capture depends strongly on molecular size. For dipeptides, no intact reduced species were observed; the predominant ions correspond to loss of hydrogen and ammonia. In contrast, the intact reduced species was observed for larger peptides. Calculated structures indicate that the diprotonated dipeptide ions form largely extended structures with low probability of internal ionic hydrogen bonding (i.e., charge solvation) whereas internal ionic H-bonding occurs extensively for larger peptide dications. Solvation of the peptide ions with between one to seven methanol molecules reduces the total extent of H loss even for dipeptides where intact reduced species can survive more than a microsecond after electron capture. The yield of ions corresponding to cleavage of NCalpha bonds (c+ and z+* ions) does not depend strongly on peptide size but decreases with the extent of microsolvation for the dipeptide dications. H-bonding appears to play an important role for the survival of the intact reduced ions but less so for the formation of c+ and z+* ions. Our results indicate that electron capture predominantly occurs at the ammonium groups (at least 70 to 80%), and provides important new insights into the electron capture dissociation process.

Antimicrobial Cationic Peptides↗